The present invention relates to a semiconductor power module, on which power semiconductor elements such as insulated-gate bipolar transistors (referred below to as IGBT) or the like are mounted, an inverter/converter including the same, and a method of manufacturing a cooling jacket for mounting the semiconductor power module.
It is required that a semiconductor power module used for inverter/converters mounted on a wind power generator be efficiently cooled because of a large amount of heat generation, and liquid cooling is effective as cooling means therefor. The liquid cooling is accomplished usually by bonding fins to a semiconductor power module with, for example, thermal grease therebetween and immersing the fins in a flow passage of cooling water. However, the thermal grease has a disadvantage that it is large in thermal resistance as compared with metals.
In contrast, in order to ensure a higher cooling capability, there is known a semiconductor power module of direct-cooling method, in which heat is transferred to parts being cooled, without thermal grease therebetween, to achieve cooling (refer to, for example, JP-A-2007-295765 and JP-A-2009-44891).
With the semiconductor power module of direct-cooling method, a power semiconductor element(s) is mounted directly on an upper surface of a heatsink with an insulated layer therebetween and fins are provided on an underside of the heatsink. Hereupon, owing to that construction, in which an opening on the upper surface of the cooling jacket is covered and closed by the underside of the heatsink, the underside of the heatsink is brought into direct contact with a cooling water, so that the heatsink is improved in cooling effect.
In JP-A-2007-295765 and JP-A-2009-44891, connection to motor(s) mounted on a vehicle is assumed, and a condenser module is provided on a separate surface from a cooling jacket and having the same foot-print size as that of the cooling jacket, which is covered and closed by the heatsink of the semiconductor module, except an inlet/outlet whereby an inverter/converter is made minimum in foot-print size.
Since the condenser module is provided on the separate surface from the cooling jacket, however, an interconnection length of a conducting plate for connection between a DC terminal of the semiconductor module and a DC terminal of the condenser module is lengthened by a difference in level between a plane of the cooling jacket and a plane of the condenser module. When the interconnection length of the conducting plate is lengthened, an increase in value of resistance is brought about in proportion to the length to cause an increase in loss.
In such case, since an inductance making a current-resistance is further increased, for example, between a condenser of a DC circuit and IGBT, jump-voltage is generated with a change in current in switching and thus there is suggested a possibility that IGBT is broken in the case where the rated voltage of IGBT is exceeded.
JP-A-2008-206243 discloses a construction, in which a condenser module is arranged on the same plane as that of a cooling jacket, in which a heatsink of a semiconductor module is covered and closed from laterally. As compared with the disclosure of JP-A-2007-295765 and JP-A-2009-44891, a decrease in inductance can be achieved by shortening a wiring distance between a condenser and IGBT but assembling is problematically poor in quality because of that construction, in which the semiconductor module is mounted from laterally.
JP-A-2009-219270 discloses a construction, in which an opening on an upper surface of a cooling jacket is covered and closed by the use of a flange portion of a semiconductor module of a double-sided direct cooling method, in which a power semiconductor element is interposed by two heatsinks, and a condenser module is arranged on substantially the same plane as that of the cooling jacket. As compared with the disclosure of JP-A-2007-295765 and JP-A-2009-44891, a decrease in inductance can be achieved by shortening a wiring distance between a condenser and an IGBT but scattering in cooling performance becomes problematically large since a gap tolerance between the heatsinks and the cooling jacket becomes large in the case where the condenser module is not high in accuracy of positioning relative to the cooling jacket.